:root {
    --primary-color: #4D77FF;
    --secondary-color: #2B333B;
    --accent-color: #FF6B6B;
    --success-color: #4CAF50;
    --warning-color: #FFA726;
    --info-color: #29B6F6;
    
    --text-primary: #2B333B;
    --text-secondary: #71777D;
    --text-light: #B7BBBF;
    
    --bg-primary: #FFFFFF;
    --bg-secondary: #F8F9FA;
    --bg-dark: #2B333B;
    
    --border-color: #E8ECEF;
    --shadow-sm: 0 2px 8px rgba(43, 51, 59, 0.08);
    --shadow-md: 0 4px 16px rgba(43, 51, 59, 0.12);
    --shadow-lg: 0 8px 32px rgba(43, 51, 59, 0.16);
    
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Microsoft YaHei', sans-serif;
    color: var(--text-primary);
    line-height: 1.6;
    background-color: var(--bg-secondary);
}

a {
    text-decoration: none;
    color: inherit;
    transition: all 0.3s ease;
}

img {
    max-width: 100%;
    height: auto;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* 按钮样式 */
.btn {
    display: inline-block;
    padding: 10px 24px;
    border-radius: var(--radius-sm);
    font-weight: 500;
    font-size: 14px;
    border: none;
    cursor: pointer;
    transition: all 0.3s ease;
    text-align: center;
}

.btn-primary {
    background-color: var(--primary-color);
    color: white;
}

.btn-primary:hover {
    background-color: #3A5BD0;
    transform: translateY(-2px);
    box-shadow: var(--shadow-sm);
}

.btn-outline {
    background-color: transparent;
    border: 1px solid var(--primary-color);
    color: var(--primary-color);
}

.btn-outline:hover {
    background-color: var(--primary-color);
    color: white;
}

/* 卡片样式 */
.card {
    background: var(--bg-primary);
    border-radius: var(--radius-md);
    padding: 24px;
    box-shadow: var(--shadow-sm);
    transition: all 0.3s ease;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-md);
}

/* 导航栏 */
.navbar {
    background: var(--bg-primary);
    box-shadow: var(--shadow-sm);
    padding: 0 40px;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.nav-links {
    display: flex;
    gap: 30px;
    align-items: center;
}

.nav-links a {
    padding: 8px 16px;
    border-radius: var(--radius-sm);
    font-weight: 500;
}

.nav-links a:hover {
    background-color: var(--bg-secondary);
    color: var(--primary-color);
}

.nav-links a.active {
    background-color: var(--primary-color);
    color: white;
}

/* 页脚 */
.footer {
    background: var(--bg-dark);
    color: white;
    padding: 40px 0;
    margin-top: 60px;
}

/* 工具类 */
.text-center { text-align: center; }
.text-right { text-align: right; }
.mt-1 { margin-top: 8px; }
.mt-2 { margin-top: 16px; }
.mt-3 { margin-top: 24px; }
.mt-4 { margin-top: 32px; }
.mb-1 { margin-bottom: 8px; }
.mb-2 { margin-bottom: 16px; }
.mb-3 { margin-bottom: 24px; }
.mb-4 { margin-bottom: 32px; }